Disposable cover for tonometer

Abstract

A disposable protective cover (100) for application to an applanation tonometer head (20) of a Goldmann-type applanation tonometer (10). The disposable protective cover (100) may be bag like in contour or preferably pre-formed into a frusto-conical contour having a planar surface (102) bounded by a conical surface (104) which substantially matches the planar surface (22) and the conical surface (24) of applanation tonometer head (20). Disposable protective cover (100) includes at least one tab member (130) for use in handling tonometer cover (100) during application and removal therefrom. Protective cover (100) in general and the planar surface (102) in particular must fit tightly to applanation head (20), be optically transparent, and sufficiently thin so as not to interfere with the tonometer measurement. Protective cover (100) is releasably secured to applanation head (20) by a double-backed removable adhesive strip (140) which is located on the conical surface (24) of applanation tonometer head (20).

What is claimed is: 
     
       1. A disposable protective cover for application to an applanation tonometer head having a substantially frusto-conical contour defining opposing ends having a smaller diameter end and a larger diameter end including a substantially planar surface bounded by a conical surface, comprising: a. a sheath member having a predetermined contour for contiguous interface with said tonometer head, said sheath being formed from a substantially optically transparent composition having a predetermined thickness for minimizing tonometer measurement interference, said sheath member being formed of a plastic composition and pre-formed into a substantially frusto-conical contour having a thickness dimension within the approximate range of 0.00025 to 0.002 inches, said sheath member being inserted on said tonometer head in a predetermined direction;   b. releasable retention means for releasably coupling said sheath member to said conical surface of said tonometer head, said releasable retention means including a retaining ring having an internal conical surface insertable on said tonometer head for clampingly retaining said sheath member between said retaining ring and said conical surface of said tonometer head, said retaining ring having an increasing internal diameter for insertion on and frictional engagement with said tonometer head when said retaining ring is slidingly engaged with said tonometer head in said predetermined direction extending between said tonometer head smaller diameter end and said larger diameter end; whereby said sheath member is sufficiently stretched by said insertion of said retaining ring on said tonometer head to provide a taut covering for said planar surface of said tonometer head.   
     
     
       2. The disposable protective cover as recited in claim 1 wherein said sheath member includes at least one tab formed thereon. 
     
     
       3. The disposable protective cover as recited in claim 1 wherein said disposable protective cover is enclosed by a package having at least one wall member removable therefrom. 
     
     
       4. A kit for providing a sterile cover for an applanation tonometer head, said tonometer head having a substantially planar portion bounded by a conical surface, comprising: a. package means having a sterile interior for enclosing a sheath member, said sheath member having a substantially frusto-conical contour for covering said flat portion of said tonometer head and at least a portion of said conical surface, said sheath member having at least one tab member and being formed by a thin, optically transparent, plastic composition, said sheath member having a thickness dimension within the approximate range of 0.00025 to 0.002 inches, said package means having one wall member wherein a portion of said wall member is formed integrally in one-piece formation with said sheath member;   b. releasable retention means for releasably coupling said sheath member to said conical surface of said tonometer head, said retention means being enclosed within said package means.   
     
     
       5. The disposable protective cover as recited in claim 4 wherein said retention means includes an elastomeric band fixedly coupled to said sheath member for frictionally coupling said sheath member to said conical surface of said tonometer head. 
     
     
       6. The disposable protective cover as recited in claim 4 wherein said retention means is fixedly coupled to said tab. 
     
     
       7. The disposable protective cover as recited in claim 6 wherein said retention means comprises a latch and hook fastener having at least one latch member and at least one hook member, one of said latch or hook members being fixedly coupled to said conical surface of said tonometer head and the other of said members being fixedly coupled to said tab. 
     
     
       8. The disposable protective cover as recited in claim 6 wherein said retention means includes a double-backed removable adhesive tape strip for providing said releasable coupling of said sheath member to said conical surface of said tonometer head. 
     
     
       9. The disposable protective cover as recited in claim 6 wherein said retention means includes a removable adhesive coating. 
     
     
       10. The kit as recited in claim 4 wherein said package means further includes at least one package housing member for containing said sheath member therein. 
     
     
       11. The kit as recited in claim 10 wherein said package means includes a shield member releasably coupled to said wall member for protecting an interior portion of said sheath member. 
     
     
       12. The kit as recited in claim 10 wherein said wall member includes a perforation surrounding said sheath member to permit separation of said sheath member from said wall member. 
     
     
       13. A method of providing a sterile and disposable protective cover over a contact portion of an applanation tonometer head, said protective cover being provided from within a package having a removable wall and an underlying wall, comprising: a. locating said protective cover within said package, said protective cover defining a sheath member being formed of a plastic composition and pre-formed into a substantially frusto-conical contour having a thickness dimension within the approximate range of 0.00025 to 0.002 inches;   b. removing at least a portion of said removable wall from said package;   c. removing said protective cover from said package by grasping at least one tab member formed on said protective cover and separating said protective cover from a portion of said underlying wall of said package, said protective cover having been integrally formed in said underlying wall in one-piece formation;   d. using said tab member as a handle, sliding said protective cover over said tonometer head until a substantially planar portion of said protective cover engages said contact portion of said tonometer head; and,   e. releasably coupling said protective cover to said tonometer head.   
     
     
       14. The method according to claim 18 where the step of removing at least a portion of a wall from said package includes the step of removing a protective shield from said package to expose said protective cover.